Lecture 2: Viral Replication Flashcards
What happens in the first stage of viral replication? 1- attachment
Spike proteins from enveloped viruses attach to specific receptors of the host cell membrane
Non-enveloped viruses via direct capsid contact (docking port) to host cell receptor
What happens during the second step of viral replication?
2-penetration
Virus or its genome enters the host cell cytoplasm.
enveloped= FUSION
only naked viruses = DIRECT PENETRATION
Only enveloped viruses = ENDOCYTOSIS then to an early endosome then to fusion
What happens during the third step of viral replication? Where does it occur?
uncoating / eclipse
Uncoating of the lipid membrane and protein capsid.
- at the cell membrane
- within cytosol by enzymes
- within the endocytic vesicle by enzymes, pH, viron conformational change.
What happens during the 4th step of viral replication?
What do some viruses often shut down during viral replication?
Transcription to produce mRNA
-rna-dependent dna polymerase (Reverse transcriptase) (Retroviruses & para-retroviruses)
-rna-dependent rna polymerase (dsRNA & ssRNA (+) (-))
-dna-dependent dna polymerase (dna to dna)
*some viruses often shut down host nucleic acid replication and protein production (b/c it creates more opportunities for virion production)
All viral genomes must be able to
-serve as a template to produce new viral genomes
-produce mRNAs
What happens during the 6th step in viral replication?
assembly
-creation of a nucleocapsid
-happens spontaneously (ASAP)
-include a packaging sequence (This signals the start of packaging the genome inside of the capsid) (start to organize)
What is the 7th step of viral replication?
release
-budding: enveloped
-lysis: ONLY T-CELLS/ enveloped/naked
-exocytosis: enveloped/ naked
the release may depend on the virus morphology
antiviral therapy mAbs affect what step of viral replication and which viruses?
2nd step through entry (adsorption or fusion)
-HIV, CMV, RSV
antiviral therapy called entry inhibitors affect what step of viral replication and which viruses?
First step
-HIV
-CMV
-RSV
mAbs = immunotherapy (stimulating the immune system) while entry inhibitors prevent the virus from entering the cell yet both of these antivirals happen during entry (Absorption or fusion)
antiviral therapy called uncoating inhibitors affect what step of viral replication and which viruses?
-uncoating
-FluA
-picoronaviruses
Which antiviral therapy affect the replication step of of viral replication?
-RT inhibitors (HIV, HBV)
-viral DNA polymerase inhibitors
-viral RNA polymerase inhibitors
Antiviral therapies called protease inhibitors affect what step of viral replication?
-maturation (HIV)
-Replication (HCV)
Antiviral therapies called integrase inhibitors affect what step of viral replication?
Integration of viral genome (HIV)
Antiviral therapies called neuraminidase inhibitors affect what step of viral replication?
Release (step 7)
-influenza virus
(Neuraminidase and hemaggultinin are the two types of spike proteins seen)
What are the 4 Consequences of mutation?
- Allows viruses to alter their tropism (covid= bats to humans. Influenza pigs = humans)
- Alter their antigenic properties (helping to hide from immune system) (influenza = antigenic drift)
3.drug resistance (HIV drug requires antiretroviral therapy) (influenza does not work anymore w/ amentidine) - virulent more/less (influenza becomes deadly in humans after jumping from pigs to pigs)
